Electrode



Dec- 4, 1928.

1,693,794 H. w. MATHEsoN Er M Y ELECTRODE Filed Auz- 23. 1924 v l l f QY HIbr/ney Patented Dec. 4, 1928.

UNITED sTATEs'f PATENT OFFICE.

rI-IOYARD W'. MATHESON AND JULIAN O. SMITH, 0I MONTREAL, QUEBEC, CANADA.

ELEQTRGDE.

Application sied August 23,. im. ,serial` Nn. 738,721.

This invention relates broadly to improvements 1n electrodes, and moreparticularly to electrodes for use in electric steam generating orwater, lheating units ofthe water resistance type. f

l, The primary ob'ect of this invention is tok rovide a construe ion ofsuch a type that the ormat-ion of non-condensable gases, principallyhydrogen and oxygen, is greatly reduced or eliminated.

Ay further object of the invention is to secure as nearly as possible a,uniform cur.- rent density over the Whole surface of the electrode andin the Water itself between the elect-rode. Y y

A still further object of the invention is toy prov-ide construction ofsuch a type as to ensure a vigorous circulation of the Water. n Theelectrodes at presentin use in Water resistance electric steamgenerators, such as shown inSwiss Patent No. 30,925 to ReveL'are usuallycylindrical members disposed axially vertically rat such distance from acomplementary electrode that a discharge may take place throughintervening water, and it was previously supposed that the currentdensity wasapprcximately uniform over the entire` surface and that theelectric discharge took if place without arcing. It has been, however,

discovered that althou Y l1 the two electrode surfaces may be paralleil,the currentv density of the surface is by no means uniform, beinggreatest at the bottom.. This non-uniformity of current density is nowbelieved to be due tol electro-dynamic forces and rto the largevolume ofsteam arising over the surface of the inner electrode, the insulatingeffect ofthe Steam increasing with the height of the electrode.Therefore, the current density becomes much greater at the bottom Wherethe steamlrn is thinnest and increases to such a point that eroinertakes place under ordinary conditions. Thermal decomposition of thesteam results and 'coolingof the gases takes pla-ce so rapidly thatrecombinatiouof the hydrogen yand oxygen is not effected. Rapiddeterioration of ythe lower parts of theelectrodes is experienced; andfurthermore, the circulation of the water. in the boiler is ratherpoor.k .s f

The factors contributing towards the formation of hydrogen and oxygen inthe steam may therefore be classified as follows (1,) Non-uniformcurrent density of the electrode until arcing takes place,causingthermal'decomposition of the Water vapour. (2) Overheating of theelectrode itself,

due to the poor circulationof the Water and the non-uniform currentdensit It has beenrdiscovered that in the operation of an electricboiler of the type described, the voltage drop is largely'at the surfaceofthe highl tension electrode and therefore the largest evolution ofsteam is at the surface of the electrode; with the result that if thesteam' is allowed to remain in Contact kwith the discharge surface oftheelectrode, it forms an' insulating jacket around the electrodeincreasing in thickness from the bottom to the ktop of the electrode andthereby increasing the current density at theloiver end ofthe electrodewhere the steam film `is thinnest. This increase or concentration ofcurrent density is belicvedto be largely responsible for the arcingwhich has been foundv to occur. The quality the Water is also aconsiderable faotor'in the arcing tendency at any definite voltage. If

the Water 1s impure giving lowlresistance, the voltage should be loweredin order to ma1n `tain the current density below the point at `whichareing begins.

eliminate arcing and the formation of noncondensable gases by ensuring agreat uniformity of current density from topl to, bottolnof theelectrode and by removal of steam from the discharge surface of theelectrode. The accompanying drawings show scvcl'alof the many forms`which the electrode may takel inorder to produce these results.Brieflyit may be stated vthat the electrode instead of being a singlecontinuous surface is ypreferably madeup of a number of separateAmembers or segments with the objectof rpresenting a numbery of separatedisrharge surfaces ivith channels between 'tor the escape ol steam.These surfaces are so disposed that the separationol steam therefrom isYfacililated and the steam permitted to ris-e Without passing` over thedischarge surfaces above. rl`he arrangement also has the disadvantage.of' ensuring' better circulation of vater in the boiler with consequentellective cooling of the e.- ftrode.

ln the accoinpanvingry drawings Aillustrating' certain, but b v no meansall possible7 einl'iodimcnts et the invention :M

Fir'. l is a vertical sectional. viev.' of a boilei` with the improvedelectrode therein.

Fie". Q is a cross sectional vienv on the line Q-QQFiefure l.

Fiejs. 3, l and 5 are viewsshou'ing on an enlarb'ed sifale compared withFigure l,

various forms of electrode segments.

Rete `ring` more particularly to the dra2vings. ll desigA .ates uboil-er provided with an inner shell or lining` lf2, spaced from theboiler but eleetiicallfv and mechanicallvv connected thereto. The lo verend olI the boiler ma)- be provided with a thnvnivardljvv extendinglerev or settling` chamber 13. from vv'hif'h a. bleeding pipe il leadsfor discharge of surplus or inpure vvater to regulate the level orelectric coiiductivitv of the Water in the boiler. Tater ma)r beadiritted to the boiler by any suitable means as through a pipe l5having communication 'with the interior of' the boiler at points aroundthe si rfa/ce thereof.

For purposes ot illustration onlj,T one elect iode is shown disposedeoncentricallv in a boiler. and majv be regarded as connected in asingle phase circuit or to one phase ot a two-phase. three-phase. orpoly-phase circuit, and the boiler muy be regarded as conueeted toanother phase or as nroum'led. lt will be understood that tho inventionapplies to anyv arrangement ot electrodes, i. e., one or more to aboiler and that the dis-- charge may be between the eletrode and theboiler or between an electrode and a coinpleinentai,r Aground membernithin the boiler or between concentricallv arranged similar electrodes.

The form ot electrode illustrated coniprises a central stem 1G and aseries ol reed i'irusto-conieal plates 1T, or equivalents. supported insuitable manner troni the central stem which ma;7 also serve as anelectrical conductor Yfor all the plates. lt ivill be understood.hovvever. that the plates ma)Y be Ainsulated from the stein and suppliedwith current by a separate conductor. PreferablyY the plates increase inoutr'de and inside diameter from the lower-most ip vards but there maj;be no in'r i ease in either (haineter or the increase nav be in onli.von. diameter. Also. the p ates are preferablyv siibstantiallj.vparallel, and if desired the lower-most magv be substantiallj.v conicalas shown. rVlie outer edges o'l` the plates are prelerablv rounded butmaxv be thirst:- eiualior of bulbous cro `etion as shown at itl. Thisarrangement of plates has the advantage not onli-,V ot giving asubstantialljY uni` m distribution olf current with coolol' theelectrode, but at the same time removes the steam from the activesurla'ge ot the electrode.

Other vforms ol electrodes are shown in lligures il, #l and 5 and embodythe use of s need bars or tubes arranged in substant ally trusto-conical'form and provided with meansV tor supimrtng the same 'from the c-eitralstem lll. The structure shown in Figure 3 embodies a single bar or tuboll) bent in spiral-helical form and connected, as by welding, to spacers2O which hold the .'arious turns of the helix in properly spacedrelation and which are in turn mounted on the arms ot a spider or othersuitable contrivanee tor supportineT the structure from aeentral stem.

Figure l; disfloses a structure dillerincf from F l only in that the barthat ol" Figure or tube lil is replaced by a series ol rings 2l securedto the supports 20.

Figure 5 shovvs an arrangement ditlerin.r from the prt-cedingT .figuresin that the bars composingY the discl'iarc'e surface are arranged topoint toward the. focal point of the. trustmconical structure instead ofextending cireuinterentiallv as in the previous lorms. i

In all these modifications excellent coolingv is obtained but theconstruction not as advantageous as the solid plate construction onaccount of the tendone)v for steam to riso between the bars andtheretoife through the disfl'iarjgro Zones. To avoid vthis condition asmuch as possible the barsy should be closely spaced.

The evolution ot steam is greatest u the surface of the electrode. aspreviously lained, and therefore in the present seg:- mental type ofelectrode the discharge is betvvein the outer surfaces of the electrodesegments und the inner shell. Steam formed at these outer surfaces risesinto contact with the inner surface of the segment next. above and flowsthence upwardly through the central orince of the annular segnient andthrough the correspon dintr orifices ot all segments above. ln no raseshould the steam `generated at a lower segment flow in :mvVyconsiderable amount: over tl e acti ve surface ot any segment above. Thegradual increase in diameter of the see-ments from the lowest to thehighest While not essential is advantageous and serves tivo purposes:Firstly, it: ensures that little or no stam risingr from b leu vvillflou' through the discharge Zone segments abov and seeondlv. it provdesa central pass through the electrode. the cross sectional area of whichpassage inlof) `less than one part.

creases from bottom Ata'top to accommodate the increasing volume ofsteam toward the top. The establishment of ay denite current ofLsteamrising through the centre of the electrode induces a vigorouscirculation of water in the boiler, which circulation of water servestouniormly cool the electrode and also to maintain the conductivity ofthe water substantially uniform throughout the boiler.

Many modifications may be made in the form of the electrode segments ordivisions, and it will therefore be understood that the invention is notlimited to the details of construction and arrangement hereinillustrated, but embraces all modifications and arrangements whichproduce the results above described.

By the use of electrodes of the general design above described, it isfound in actual practice that the amount of non-condensable gases,principally hydrogen and oxygen, is greatly reduced. The amount ofhydrogen developed in an electric boiler of previously known design hasbeen found to run between 10 to 50 parts per 1,000,000 parts of steamproduced, or even more; whereas with an electrode of the type describedand with Water of the same characteristics, the free hydrogen drops, tog to 5 parts per 1,000,000 parts of steamk and is usually This reductionis obtained with a definite type of water and definite current density,and it is to be understood, of course, that the amount of hydrogen willvary depending on the characteristics of the water and the currentdensity. The folowing example of resultswill serve to illustrate.

Using an installation comprising three boilers each connected to onephase of a three-phase systempand a good commercial water, it is foundthat with a voltage of 6,000 and total amperage of 2,200, givingr about24,000 kilowatts tot-al input at an average current density of .5amperes per ysquare inch, that the average of hydrogen gas produced in aseries of ten tests was .S5 parts per 1,000,000 parts of steam produced,which is approximately the same amount of hydrogen as that found insteam from ordinary coal-fired boilers.

Having thus described our invention, what we claim is v l. An electrodefor water resistance steam generators and the like. comprising a seriesof annular superposed spaced discharge members and a central conductingand supporting stem connected to `said members at intervals around thecircumference theredf, whereby a steam passage is formed Within theannul, continuous from top to bottom of the electrode.

2. An electrode for water resistance steam generators and the like,comprising a series of superposed annular {ruste-conical dis` chargemembers increaslng 1n diameter pmgressively from the lower-most, and aconducting and supporting stem therefor disposed within the imnulaa 3.An .electrodc'for water resistance steam generators and the like,ycomprising a series of super-posed annulaifrusto-conical dischargemembers increasing in diameter progressively from the lowermost andsupporting means therefor disposed within the annulae.

4. An electrode for water resistance steam generators and the like,comprising a series of superposed annular discharge plates rounded attheir outer edges, and a conducting and supporting stem therefordisposedwithin the annulae.

5.. An electrode for Water resistance steam generators and the like,comprising a series of superposed annular discharge plates thickened androunded at their outer edges, and a conducting and supporting stemtherefor disposed within the annul.

` 6. An electrode for water resistance steam generators and the like,comprising a series of frusto-conical annular plates thickened androunded at their outer edges and nested in spaced relation, and meansfor supporting the plates.

7. An electrode for water resistance steam generators and the like,comprising a series of frusto-conical annular plates nested in spacedrelation and progressively increasing in outside diameter from thelowermost plate upwards, and means for supporting the plates andconducting electric currentto or from the same.

8. An electrode for water resistance steam generators and the like,comprising a series of super-posed electrode members adapted to bedisposed at different distances from a complementary electrode, theactive surface areas of such members being proportioned to the distancefrom the companion electrode, the direction of current flow and theconductivity of water at different levels, to the end that asubstantially uniform current density is obtained at all parts of theactive surface of the electrode.

9. An electrode for water resistance steam generators for use Wit-hin acomliilementarv vdefining a vertically disposed upwardly enlarging steamflow passage, said body having passages inclining upwardly from itsactive surface and leading into the vertical passage for transfer ofsteam from the acllilive snrl'uce ol die electrode inlo the verticalpassage.

ll. An electrode Comprising a seires of upwardly tapering hollow membersurrzingjed in superposed relation and increusingjr progressively indiameter from the lowermostJ said members combining to deline a passageincreasing' in size .from lhe holloni uinvnrdly, and menus connectingthe inemhers together. 10 In witness whereof, we hare hereunto set ourhands.

HOVARD YV. MATHESON. JULIAN C. SMITH.

